Dave, > Bernie is retired from advertising. > I'm a retired engineer and researcher. > > When Bernie describes something he likes, it's a full-court-press sales pitch. > When I describe something (I like or dislike) I can't bring myself not to > present the other side as well.
Now, that's somewhat of an exaggeration...you haven't seen my full-court-press sales pitch. And, I notice you do a pretty good job of selling your agenda, as well. :-) > (b) Dan & Bernie have pioneered a way to use it to match a set of shafts > for building a set of clubs. The matching is much faster and at least as > accurate as frequency matching -- possibly more accurate. Dan did the shaft matching pioneering. I just jumped on the technique because it's so fast, easy, and Dan tells me it's also accurate, when checked against his FA. > I also have some problems with Bernie's statements about spines. A couple > of days ago, Bernie and I agreed that we both believed in John Kaufman's > statments about spines in his tech notes. Apparently we didn't agree on all > of them. You can see them at http://www.csfa.com/techframe.htm. Pay > particular attention to the note on "Inverted flex board"; that has John's > more rigorous and quantitative explanations -- and the important > conclusions which are the ones I said I agree with. Here's a copy of those > conclusions: Here're the quotes from John's site that I find applicable to the discussion: "In a spine tester when the shaft is bent it will attempt to rotate such that it is being bent in its weakest direction. During the swing, the club for the most part bends in the direction of the swing plane. If the weak axis is lying in this plane there will be little tendency for the shaft to rotate during your swing as it does in a spine finder. I don't know how strong this rotational tendency is but why not minimize it?" And: "A number of clubmakers recently reported very good results with very poor shafts when the spine was properly aligned. These shafts had frequency variations of up to 15 cpm! I checked with my local shaft purveyor and tried to buy the crummiest shafts I could find. Unfortunately their worst shafts were pretty good. I sorted through a pile of them and found two that had an eight cpm variation. One had a weak axis of 250 cpm (other axis at 258) and the other a strong axis of 250 cpm (other axis at 242). I built two identical drivers with both 250cpm axes pointed at 9:00. In one case the strong axis was at 9:00 the other the weak axis at 9:00. I tried a blind test and the weak axis at 9:00 was definitely the preferred alignment. " > A couple of specific comments on Bernie's points... > >With a frequency analyzer, you > >have to locate the NBPs and spines on every shaft in a spinefinder first, > >then frequency match and as you tip trim, the spine location can move and > >you have to re-spine the shafts again. > > Simply not true! > If you believe JK's tech notes, you get a more accurate spine location from > the frequency meter. If you use a spine finder, you can only consider it a > starting point, to save you some time finding the REAL spine with the > frequency meter. Well, as you suggest above, if you want to spend a lot of time clamping and unclamping, I suppose you could use the FA the same way you use the NF2. But, if I had an FA, I would surely have a spinefinder to save me time in locating the S1 and the NBP positions. Why just a "starting point?" On my NF2, I can read the deflection at any point on the shaft's circumference to within .002" (with some care). If .0035 is the equivalent of 1 cpm (Dan's number), I can read to 1/2 cpm accuracy. Can you do that on your FA? > I say "mostly" because, like all mechanical spine finders, it can still be > spoofed by geometric, rather than stiffness, imperfections in the shaft. > Again, see JK's notes for more detail. Will these "geometric" imperfections ( I assume you mean something like a bent shaft?) affect the shaft's performance, and should they be taken into account in shaft alignment? Bernie Writeto: [EMAIL PROTECTED]
